It is known to produce porous strips by means of a paper-making technique, said strips including fibres such as cellulose fibres, and their porosity generally being adjusted by a pore-forming product.
Such fibres made by said paper-making technique are suitable for developing both physical and chemical links between one another so as to form a felt with good mechanical properties.
However, when it is required to apply such a technique to carbon or graphite fibres, in particular for producing electrodes for fuel cells, it is impossible to obtain layers which have sufficient cohesion.
Such an impossibility results in particular from the linear structure of the carbon fibres and from the lack of chemical links between fibres which make it impossible for said fibres to branch out into each other to form an assembly which has satisfactory cohesion.
For electrode production, adding cellulose fibres to the carbon fibres has been proposed; however, very thin strips cannot be obtained by this method and further, electron conductivity is low since the points of contact between the conductive fibres are then very few.
The applicants have succeeded in contriving a paper-making technique for continuously producing thin, porous, conductive strips based on carbon or graphite fibres on an industrial scale, said strips possibly comprising a plurality of very thin layers, and said method avoiding the use of poreforming products, water being the only dispersive agent used.
Purely by way of non-limiting illustration, the method of the invention can be used to manufacture electrodes for electric cells, and in particular for fuel cells, in which current is drawn by means of a collector of electronic conductivity having points or lines of contact spaced apart at a distance of about one millimeter.